1. Dogs recall their owner’s face upon hearing the owner’s voice;Adachi;Anim. Cogn.,2007
2. Cues to food location that domestic dogs (Canis familiaris) of different ages do and do not use;Agnetta;Anim. Cogn.,2000
3. American Pet Products Association. (n.d.). Pet Industry Market Size & Ownership Statistics. http://www.americanpetproducts.org/press_industrytrends.asp.
4. American Pet Products Manufacturers Association (APPMA). (2004). National pet owners survey. http://www.appma.org.
5. Obesity in the dog and cat;Anderson;Vet. Annu.,1974